Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Mountain Biking Mountain biking is one of the fastest growing sports in the world. Check out this forum to discuss the latest tips, tricks, gear and equipment in the world of mountain biking.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 11-03-08, 02:09 AM   #1
sunburst
Senior Member
Thread Starter
 
sunburst's Avatar
 
Join Date: Jan 2008
Location: NorCal - bay area
Bikes: giant, trek, peugeots, friday
Posts: 1,320
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
physics, fenders and mud

This really has very little to do with mt. biking, but who else is really going to really appreciate mud, besides you guys?

This is about my recent decision to being car-free, and my new fenders, just installed Thurs, so I can cycle through the winter. Well, we had our first real rain Sat, but today (Sunday) was great so I cycled out to the farmer's market and took the long way home around the bay. Went off-road for fun and very quickly remembered that the levies around here turn into this thick sticky mud. I had street tires on my old rigid-fork Rockhopper so I thought I was cool with the mud. Plus my fenders were going to protect me - right?

Within 30-40 feet I had collected so much mud I was slipping and sliding. A few feet more and I seized up. I mean the damned wheels wouldn't even turn - mud in the brakes, fenders, everywhere. And not a stick in sight! So I tried dragging the bike up a hill to a paved bike/pedestrian trail and the bike felt like it weighted at least half a ton more than normal. Finally got enough mud off it to start turning the wheels and eventually found a branch a quarter mile or so up the trail.

So anyway, while brushing up on physics a few hours later (hey, what do you do in your spare time!?! - actually I'm just trying to help my son survive high school), I read this section on rolling vs sliding friction and the advantages of the wheel. From my old college text: "in rolling, the microscopic contact welds are 'peeled' apart rather than 'sheared' apart as in sliding. This will reduce the frictional force by a large factor."

Oh.
sunburst is offline   Reply With Quote
Old 11-03-08, 02:13 AM   #2
kmart
Blue Light Special
 
kmart's Avatar
 
Join Date: Sep 2006
Location: Bay Area, Sunny Cali
Bikes: '05 Felt F55, Schwinn Prologue road bike, '86 Centurion DS Iron Man, Sette Flite AM MTB
Posts: 1,467
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Pardon me, but what does that quote about peeling vs sliding friction have to do with the mud caked around your fenders and tires? I mean, I guess with all that mud stuck to you you're trying to "shear" mud instead of rolling over it, but at that point you probably aren't going very fast anyway because you've completely lost control.

When you say street tires you mean slick treads right? Seems like a bad decision for mud - you'll cut right to the bottom of it start sliding around all over the place. Put some knobby tires on, the fatter the better, and try that muddy section again.

Last edited by kmart; 11-03-08 at 02:23 AM.
kmart is offline   Reply With Quote
Old 11-03-08, 03:46 PM   #3
sunburst
Senior Member
Thread Starter
 
sunburst's Avatar
 
Join Date: Jan 2008
Location: NorCal - bay area
Bikes: giant, trek, peugeots, friday
Posts: 1,320
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
You're right, sliding/peeling got nothing to do with the fenders, except that the mud in the fenders stopped the wheels. The sliding happened when the wheels stopped turning and I tried to drag the bike along the trail. I know I had the wrong tires. I wasn't thinking about mud when I started off-road because most of the trail is pretty decent gravel hardpack.
sunburst is offline   Reply With Quote
Old 11-03-08, 03:49 PM   #4
sunburst
Senior Member
Thread Starter
 
sunburst's Avatar
 
Join Date: Jan 2008
Location: NorCal - bay area
Bikes: giant, trek, peugeots, friday
Posts: 1,320
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
xx

Last edited by sunburst; 11-03-08 at 09:24 PM.
sunburst is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 11:52 AM.